How To

How do firewalls prevent computer viruses?

Written by a NortonLifeLock employee


You’ve likely heard the word ‘firewall’ used to describe a measure of prevention against cyber criminals. But that doesn’t mean you know how a firewall actually works, does it?

Don’t worry—the truth is that most people don’t how a firewall works; they just expect it to do its job. But it’s actually a lot simpler than you might think. Once you learn a little more about firewalls, you might feel more confident about installing one on your home computer, if you haven’t already. If you’re already using a firewall to prevent cyber attacks, perhaps learning more about how it works will improve your ability to manage the firewall with greater personalization at home and in the office.

What Is a Firewall?

It’s not really a wall at all—it’s more like a filter. It would actually be more accurate if firewalls were called ‘firefilters’ because they’re not built to keep  everything  out. Instead, firewalls are designed to  filter threatening communications.

Firewalls function using a system of either inclusive or exclusive parameters, allowing specific types of communication in or excluding others. Generally, a firewall is controlled by an access control list, which has a particular set of guidelines that allow or resist access to specific computer communications. These guidelines can be customized to fit any need on just about any device capable of going online.

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Different Types of Firewalls

There are two types of firewalls: network firewalls and host-based firewalls. Network firewalls are typically used by businesses that contain a comprehensive network of multiple computers, servers, and users. The network firewall monitors the communications occurring between the company computers and outside sources. If a company wishes to restrict certain websites, IP addresses, or services like Instant Messenger, it can do so using a network firewall.

Aside from controlling employee behavior on office equipment, this type of firewall safeguards the sensitive internal data of the company, such as customer databases and employee information. Firewalls stop intruders from accessing this information and protect the business from cyber attacks.

Host-based firewalls work similarly but are stored locally on a single computer. Every home computer should have some kind of host-based firewall installed on it. This functions as the first line of defense against cyber criminals and various online scams and attacks.

Host-based firewalls are also recommended for business computers that are network connected but not protected by a network firewall. They can also be useful for homes with multiple computers sharing the same network.

Most of the time, home computers are covered by a hardware firewall, like a router, which protects the network. But every home computer should also have a host-based system kind in place to guard against specific types of attacks.

Host-based firewalls are easy to install and protect your computer from malware, cookies, email viruses, pop-up windows, and more. Along with desktop computers, mobile devices can be installed with firewalls to protect online activity on the go.

Mobile Firewalls

Most smartphones include basic security settings like PIN numbers. While this may be enough to keep your best friend from using your phone, it’s not ever going to be enough to ward off sophisticated online attackers.

Mobile firewalls provide a barrier against certain kinds of attacks. For example, when certain settings like file share or networking are enabled on the device, the phone is designed to respond to outside requests automatically. First of all, these settings should be kept off whenever possible. What’s more, a firewall would stop these kinds of automatic response from happening in the first place.

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